Antimicrobial activity and mechanism of isothiocyanate from Moringa oleifera seeds against Bacillus cereus and Cronobacter sakazakii and its application in goat milk

This study was conducted to investigate the antibacterial activity and mechanism of (4-[(4′-O-acetyl-α-L-rhamnosyloxy)benzyl] isothiocyanate) (RBITC) from Moringa oleifera seeds at the molecular level against Bacillus cereus ( B. cereus ) and Cronobacter sakazakii ( C. sakazakii ) and to further analyze the application of RBITC in goat milk. Antimicrobial effects were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. The changes in endoenzyme, entocyte, and cell morphology were thoroughly analyzed to reveal the possible mechanism of action. The results showed the MICs of RBITC against B. cereus and C. sakazakii strains were 0.14 and 0.25 mg/mL, and the MBCs were 0.28 and 0.50 mg/mL, respectively. Scanning electron microscopy results revealed marked destruction of the cell membrane upon RBITC treatment. The detection of intracellular substances (ATP, DNA, and proteins) and intracellular enzymes (β-galactosidase, ATPase, and AKP) exhibited the destructive effect of RBITC on bacterial cells and showed that RBITC treatment inhibits the activity of various intracellular enzymes of both strains of bacteria, resulting in disrupted intracellular homeostasis. Moreover, RBITC inhibited biofilm formation of B. cereus and C. sakazakii at concentrations of 1 × MIC, with biofilm formation found to decrease by 77.25% and 75.10% within 72 h. Finally, RBITC presented better antibacterial activity in goat milk without adverse effects on its quality. • RBITC from Moringa oleifera seeds reduced bacterial ATP and DNA levels. • RBITC caused morphological structure changes in B. cereus and C. sakazakii. • Cell membrane integrity and bacterial protein were affected by RBITC. • RBITC could inhibit the growth of B. cereus and C. sakazakii in goat milk.